This invention relates in general to the field of three-dimensional mapping and, in particular to, a method and apparatus for using continuous triggering, pulse laser reflectorless rangefinders to map three-dimensional features.
Without limiting the scope of the invention, its background will be described with reference to mapping three-dimensional geological features as an example.
Early man developed mapping techniques to define their world. Maps defined boundaries, aided trade, and allowed others to retrace the steps of explorers who had gone before them. All of these uses advanced civilization and improved the quality of life for much of the population.
As civilization advanced, so did map making technology. World exploration and military conquests fueled the need for more accurate maps. Mathematics and science allowed cartographers to take more precise measurements of features of the earth. These measurements led to better spatial relationships among geological features, which resulted in more accurate maps.
Aerial and satellite photography have changed the way people view their world. Pictures taken from above a particular location sometimes reveal that geological features are not actually as they appear on maps. The curvature of the Earth tends to compound this anomaly. Most of the differences are a result of representing a three-dimensional curved surface, i.e., the Earth, as a two-dimensional drawing. The differences are usually inconsequential for the average tourist on vacation with his family. Scientists and engineers, however, encounter more significant problems because of inaccurate maps. In the petroleum industry, for example, millions of dollars may be wasted on a dry hole because geological data is flawed. Three-dimensional models of particular geological features can enhance analysis accuracy and prevent mistakes caused by flawed data.
Although aerial photography has improved the accuracy of maps, it is limited by the orientation of geological features. Vertical features and overhangs, for example, are not accurately captured using aerial photography. Three-dimensional models of these features cannot be accurately generated with aerial photographs because the features cannot be observed if the camera is vertically oriented. Oblique photographs, which may be taken from the ground, create the best images of vertical features. However, current three-dimensional modeling techniques cannot model a feature using an image taken from an oblique angle.
Near-vertical and overhanging features are also difficult to represent spatially because a researcher must first locate a Global Positioning System(GPS) receiver on the feature before it can be located. These features may be difficult or impossible to accurately measure because of rugged terrain. However, researchers may easily study features located in rugged terrain if they have a three-dimensional photorealistic model. These models, however, may not be accurate. Furthermore, the systems used to generate the models are generally very expensive. Some of these three-dimensional photorealistic modeling systems that are currently available use laser range finders to locate a remote geological feature. The most common system transmits a laser beam to a point on the feature and calculates the distance from the transmitter to the point. These systems are limited because they inefficiently take point by point measurements of a feature. The researcher will occasionally return from the field to find that one or more of the points measured is not the desired point. A failure to capture a desired point or points causes added costs and frustration because the researcher must return to the field to gather the correct data at locations that are most often very remote.
These three-dimensional photorealistic modeling systems are also limited by the number of data points that may be taken. The researcher must aim and trigger the transmitter for each desired point. Important points will be missed frequently because the researcher does not realize the significance of the point. Sometimes an important point will be overlooked completely and other times the researcher will not understand the significance of the point until the data has been reviewed in the laboratory.
Another system attempts to compensate for these inadequacies by gathering millions of data points over a given area. This system is very expensive and acquires many unnecessary data points. Although the system may paint a virtual image of the terrain, points on the image are not referenced to a known position. This information is relatively useless to a researcher because it is not correlated with other necessary or useful geological information. Furthermore, it is limited to short distances because of the large amount of useless data that is captured.
Another system uses stereographic photography or photogrammetry to model surface geometry. Such systems require multiple overlapping photographs taken at different known angles to create a stereographic view. Furthermore, photogrammetry equipment is expensive and complicated. Also, features on the resulting image are not referenced to a global position.
Therefore, a need has arisen for a mapping apparatus that does not have the expense and accuracy limitations of present mapping systems. A need has also arisen for a three-dimensional mapping system that is not constrained by a vertical camera angle. A need has also arisen for a three-dimensional mapping apparatus that does not require a researcher to physically locate a GPS receiver on a geological feature to locate the feature within a global coordinate system. A need has also arisen for such mapping apparatus that does not require a researcher to process data in the laboratory to determine if desired data points were inadvertently omitted. Further, a need has arisen for a mapping apparatus that does not fail to integrate useful information into a photorealistic model.
The present invention disclosed herein provides a three-dimensional mapping apparatus that has a signal emitter to deliver a signal to a target having at least one attribute. The attribute may be, for example, a vertical face, a fissure, an overhang or outcrop. The mapping apparatus will also have a signal receiver to receive the signal reflected by the attribute. A signal processor calculates a coordinate of the attribute relative to a global coordinate.
In one embodiment of the present invention, a method for mapping three-dimensional features includes transmitting a signal to a target and receiving a component of the signal that is reflected from the target. Signal data may be processed to determine a coordinate of the target.
In another embodiment of the invention, a three-dimensional mapping system includes a signal transmitter and a signal receiver. A Global Positioning System (GPS) may be used to determine the locations of the transmitter and receiver. A computer having a software program may be used to coordinate a data point from the signal receiver with a second data point from the Global Positioning System.
In yet another embodiment, a system for rendering a three-dimensional image may include an oblique image of a target having a control point. A coordinate of the control point relative to a known point may be determined by, for example, a Global Positioning System. A computer may correlate the coordinate of the control point to the oblique image of the control point.
In another embodiment, a mapping apparatus has a signal emitter to deliver a continuous signal to a target having at least one attribute. In geological formations, the attribute may be an outcrop, a fissure or an overhang, for example. A signal receiver continuously receives a component of the signal reflected by the attribute and a signal processor may calculate a coordinate of the attribute relative to a known coordinate. The known coordinate may be determined by a Global Positioning System.
In yet another embodiment, a method of mapping a target includes the steps of deploying a mapping apparatus and remotely commanding the mapping apparatus to emit a signal to the target. Data may be transmitted from the mapping apparatus to a remote location such as a classroom or a laboratory, for example.
In another embodiment, a mapping apparatus has a signal emitter to deliver a continuous signal to a target, which has at least one attribute. A signal receiver may continuously receive a component of the signal reflected by the attribute and a signal processor may calculate a coordinate of the attribute relative to a known coordinate. An oblique image of the target may be combined with the known coordinate.
In yet another embodiment, a method for mapping three-dimensional features may include transmitting a signal to a target and receiving a component of the signal that is reflected from the target. The component of the signal may be processed to determine a coordinate of the target and a first reference point may be assigned to a coordinate of the target. An oblique image of the target, which has a second reference point, may be coordinated with the first reference point to superimpose the oblique image over the coordinate. A map of the target may be generated by coordinating the first reference point with the second reference point on the oblique image.